HELLO THARUN
Congratulations for your result and qualifying JEE mains.since it is very difficult to predict the exact rank but we do have a backup> we have a formula to calculate the expected rank that is (100 – Total percentile) x 869010/100.So according to formula your expected rank for present percentile for January session comes out to be 20576(CRL) . Now the expected rank might change depending on the no of candidates appearing the april session. For ex if 12 lakh candidate appear the april session then just replace 869010 by 12 lakhs. But if you score above 85 percentile then you have a very decent chance of qualifying jee mains.
Now since the official cutoffs fro college are yet to be decided but let us analyse your chances by looking into the previous year cutoffs data. Since you are from tamil nadu you can avail the home state quota. Well we do not have any formula to category rank so ill be providing you the general cutoffs
NIT TRICHY
HS Chemical Engineering 12345 - 18628
HS Mechanical Engineering 4154- 12970
OS Chemical Engineering 2330- 8470
OS Mechanical Engineering 1287- 5149
Well if you look into this data then with the general category its little difficult but good newz is if we go according to the category rank then it seems that there is a very decent chance for you to get this institute.
Now i suggest you to give the april session and since you have the potential try to grab a percentile above 99.6+ so that top 5 nITS of CSE branch in your hand and more importantly there is one more exam waiting that is ADVANCE which can lead you into IITS.

But if you are curious to know that which college you might land into with your percentile then you can use the college predictor link which has following features;

JEE Main 2020 College Predictor

Know your college admission chances based on your JEE Main Percentile, Home State, Caste, Gender, etc

Including premium institutes like NITs, IIITs and CFTIs, many States/ Institutes accept admissions through JEE Main. Know your chances in states like Maharashtra, West Bengal, Delhi

Get your personalised JEE Main report with Top Predicted Colleges in JoSAA & State Level Counsellings delivered on mail

2.5 Lac engineering aspirants used Careers360 College Predictors

*B.Tech Companion*

Your one-stop B.Tech Counselling package with Full-Length JEE Main Mock Tests, 15+ College Predictors, a printed Almanac with 1000+ FAQs on Admissions & more

https://www.careers360.com/btech-companion

ALL THE BEST FOR APRIL AND ADVANCE!!